This invention relates to an armature assembly for an electromagnetic coupling such as an electromagnetic clutch. In such a clutch, an armature is connected to a driven hub by a mounting plate and is adapted to be coupled to a driving rotor when an electromagnet is excited to engage the clutch. When the clutch is engaged, the rotor acts through the armature and the mounting plate to rotate the driven hub.
In order to dampen torsional shock and vibration, the armature mounting plate is connected to the driven hub by an elastomeric ring or spider disposed between the plate and the hub. An electromagnetic clutch with an elastomeric ring or spider is disposed in Silvestrini et al. U.S. Pat. No. 4,187,939.
Difficulty has been encountered with prior electromagnetic clutches having elastomeric spiders in that, under certain abnormal conditions, the clutch may be subjected to extremely high heat. The heat melts the spider and destroys the connection between the mounting plate and the driven hub. As a result, the mounting plate and the armature may fly axially off of the hub and cause either damage or injury.